GI Pharmacology

Question 1

Antacids

Answer 1

Constipation: Al, Ca 
Diarrhea: Mg (milk of mag)
* acid rebound 
Fastest onset 
Shortest duration

Question 2

H-2 Receptor Inhibitors

Answer 2

• blocks/knocks the histamine from binding/working on the parietal cell= reduces acid production.
  H1- antihistamine (allergy)
  H2- parietal cell fxn
  -with well, long lasting
  *does not cause chelation
  *drug inx: alters body ability to absorb certain drugs in a low acidic environment- cimetidine
  -work we’ll, long lasting

Question 3

Cimetidine*

Answer 3

H2 receptor inhibitor

• inhibition: CYP450 liver enzyme that metabolizes drugs, blocks liver ability to metabolize drugs
• inhibition of ADH
• inhibition of OTC drugs

Question 4

Proton pump inhibitors PPIs

Answer 4

• blocks the release of acid into the stomach at parietal cells
• pass thru stomach intact and are absorbed in the duodenum (SI)-blood-body-GI-blood-parietal cell.
• activated by the acidic environment of the parietal cell, bind to proton pump & block release of acid
• more potent then other two

Question 5

PPIs

Answer 5

• keep Ph up for hours
• more potent than other 2
• acid stimulation signals: gastrin, histamine, ACTH
• does not cause chelation
• increase fracture risk
• decrease vitamin absorption
• headache, n/v, diarrhea, abdominal pain
• take as directed “first pass”

Question 6

Sucralfate

Answer 6

Other GI drug
* designed for ulcers
-sucrose + sulfated aluminum hydroxide forms a paste in acidic solutions
-bunds to + charged proteins in ulcer lesions
-antacid activation therapy
AE: constipation, hypophasphatemia, bezoar formation, diarrhea, abdominal cramps
-* neurotoxicity al accumulation

Question 7

Misoprostal

Answer 7

Other GI drug
* impairs gastric acid secretion and provides mucosal protection (increase bicarbonate and mucus)
* only to prevent gastric ulcers in people taking NSAIDs
-synthetic PGs
-not normally used
AEs- diarrhea, abdominal pain
** pregnancy: will cause miscarriage * medically induced abortion
0: 1 hr
D: 4-6 hrs

Question 8

Pro kinetic agents

-Metoclopramide (Reglan)

Answer 8

Other GI drug

• promote movement of the GI tract, treat gastroporesis
• Metoclopramide
• D2 antagonist*
• 5-HT agonist
• worsening of PD- causes move mung disorder
• antibiotics have pro kinetic actions

Question 9

Antacids

Answer 9

• neutralizes stomach acid on contact
• short term relief but rapid effect
• al3+, mg3+, ca2+
• chelation: binds to other + charged drugs and neither drug gets absorbed
• Neurotoxicity: Al3+ accumulation (ppl with renal impairment)
• drug inx: alters the ability to the body to absorb certain drugs in a low acidic environment, antacids easiest to work around

Question 10

Cimetidine
Ranitidine (Zantac)
Nizatidine
Famotidine (Pepcid)

Answer 10

H2 receptor antagonists

Question 11

Omeprazole (Prilosec)
Pantoprazole
Esomeprazole ( nexuim) 
Rabeprazole
Lansopeazole (Prevacid) 
Dexlansoprazole

Answer 11

PPIs